The present invention relates generally to a method and apparatus for cutting and notching hollow pipe and, more particularly, to a method and apparatus for simultaneously cutting and notching continuously formed spiral pipe.
Several pipe cutting machines use inner and outer cutters to sever a pipe or tube. These cutters are typically rotatable and have a convex or circular cutting edge for engaging the pipe. During the cutting operation, the pipe is rotated relative to the cutters or the cutters are revolved around the periphery of the pipe.
Some pipe cutting machines use these types of cutters to sever a continuously formed spiral pipe having a helical seam. Cutting machines of this type are disclosed in U.S. Pat. Nos. 4,706,481, 4,823,579 and 4,924,684, issued to the present inventor on Nov. 17, 1987, Apr. 25, 1989 and May 15, 1990. In these machines, an inner knife is attached to a boom, and an outer knife is moved into an overlapping relationship with the inner knife. As the pipe rotates and moves axially, the overlapping knives move axially with the pipe and cooperate to cut the pipe.
Spirally formed pipes are typically produced in sections of predetermined length and joined together in various ways. One method of connecting the pipe sections is to crimp one end of each pipe. The crimped end will have a slightly smaller diameter than the uncrimped end of another pipe section. A crimped end of one pipe section may then be inserted into the uncrimped end of another pipe section to connect the two sections together. An apparatus for producing pipe sections with crimped ends is disclosed in U.S. Pat. No. 4,711,110.
Another method of attaching pipe sections is to attach a flange or other type joint to the ends of the pipe sections. Flanges are desirable in that they may form air-tight connections, increase the strength of a connection and help maintain the shape of the pipe. A flange may be easily and inexpensively attached to the end of a pipe by a series of notches around the ends of each pipe section.
One present method of forming the necessary notches is to use a hand notching tool and manually notch the end of pipe sections. This method is labor intensive and may take a significant amount of time for large diameter pipes. Another option is to use a separate motorized device with a notching roller and a pipe support roller on which the formed and cut pipe may be notched. Such a device requires transporting the pipe section, mounting the pipe section onto the motorized notching device, and adjusting the pipe support roller for the size of pipe. The pipe section would also be turned around on the device to notch the opposite end. In addition to the added time and labor necessary with hand notching or a motorized notching device, a separate notching device is prone to inaccuracies both in terms of alignment of the notches with the edge of the pipe and the distance of the notch from the edge of the pipe.
Accordingly, there is a need for a pipe cutting apparatus that simultaneously cuts and notches a spirally formed pipe, decreases time and labor, and increases the precision of notches produced in a pipe.